In the main, prior art approaches to restoring competency of incompetent valves has involved venous reconstruction surgery of three basic kinds, namely, venous valve transplants, venous transposition and venous valvuloplasty.
As the term implies, the venous valve transplant approach involves the replacement of the segment of the vein having the incompetent valve with a segment of another vein having a competent valve. The venous transposition approach involves the redirection of the venous system so as to bypass an incompetent valve and venous valvuloplasty involves venous valve reconstructive surgery in which the free length of the valve cusps is reduced by plicating sutures.
These approaches to the prior art are well documented in A RATIONAL APPROACH TO SURGERY OF THE CHRONIC VENOUS STASIS SYNDROME by Harry Schanzer AND E Converse Peirce ANNALS OF SURGERY 1982, 195: 25-29 as well as in VALVULOPLASTY VALVE TRANSFER by Seshadri Raju Inter. Angio. 4 1985 419-424.
A single example on one patient of an experimental technique for treating an incompetent venous valve not involving the above types of venous surgery is described in an article by Dag Hallberg in ACTA CHIR SCAND 138: 143-145, 1972. Hallberg placed a band two to three millimetres larger than the diameter of the view around the vein.
The band was made of DACRON polyester and polyester and was applied when the patient was in the horizontal position. The band was retained loosely in position by several sutures in the venous adventitia.
Hallberg's method could not restore competence to the majority of the incompetent venous valves. In patients with venous disease, incompetent valves will usually be incompetent in the horizontal as well as the vertical positions. See, for example, FEMORAL VEIN RECONSTRUCTION IN THE MANAGEMENT OF CHRONIC VENOUS INSUFFICIENCY by Ferris E. B. and Kistner R., ARCHIVES OF SURGERY, 1982, 117:1571-1579.
Ferris and Kistner operated on 53 femoral veins in which the valves had been demonstrated pre-operatively to be incompetent. In only one case was the valve noted to be competent when the patient was horizontal at the time of operation. Kistner's approach was to suture the vein to prevent post-operative dilatation.
It is well known that by itself DACRON (Registered Trade Mark) polyester material causes marked fibrosis as well as foreign body reaction. Therefore, DACRON polyester cannot alone be considered biocompatible. In fact, DACRON polyester has been employed to stimulate fibrotic reactions which incorporate the synthetic fabric into tissue (see: S. Raju, ANN SURG. (1983) 197, 688-697).
The article REVASCULATION OF SEVERELY ISCHEMIC EXTREMITIES WITH AN ARTERIOVENOUS FISTULA by F. W. Blaisdell et al in AMERICAN JOURNAL OF SURGERY, Volume 112, pages 166-173 discloses problems associated with the use of DACRON polyester as an implantable material. In a number of cases, gradual narrowing of arteriovenous fistulas under a woven DACRON polyester sleeve was demonstrated.
In physical terms, the Hallberg approach was a static one. Once the cuff was sutured into position, no attempt was made to reduce the diameter of the vein at the valve site to restore competency of the valve. Indeed, Hallberg's single patient experiment was concerned with further dilatation of the vein at the valve site rather than reduction in the diameter of the dilated valve to restore competency.